At 1:34 a.m. Eastern European Summer Time (EEST) on June 21, summer officially began in Estonia.

The astronomical arrival of summer marks the moment when the North Pole is pointed toward the sun at a 23.4° degree angle and the sun is at its zenith, or highest point in the sky, directly above the Arctic Circle.

The summer solstice also marks the point after which days in the Northern Hemisphere will begin to grow shorter again. The day on Tuesday will be 18 hours, 39 minutes and 28 seconds in length in Estonia; on Wednesday, the sun will set approximately ten seconds earlier already.

In many parts of the world, Monday night was the first time in nearly 50 years that the full moon fell exactly on the summer solstice as well. The moon reached its fullest phase at 2:02 p.m. EEST on Monday, however, upon moonrise that night, it was nonetheless 99 percent illuminated compared to a proper full moon.